1. Field of the Invention
The present invention relates to a substrate processing system for performing processing on a substrate.
2. Description of the Related Art
The photolithography processing in manufacturing process of, for example, a semiconductor device is usually performed using a coating and developing treatment system. The coating and developing treatment system includes, for example, a transfer in/out block for transferring in/out wafers in a cassette as a unit, a processing block in which a plurality of processing and treatment units for performing various kinds of processing and treatments such as a resist coating treatment, a developing treatment, thermal processing and so on are arranged, and an interface block for delivering the wafer between an adjacent aligner and the processing block.
In the coating and developing treatment system, the wafers are successively processed in a single-wafer mode. A plurality of wafers housed in a cassette in the transfer in/out block are, for example, successively transferred to the processing block, and predetermined processing and treatment such as the resist coating treatment, the thermal processing and so on are sequentially performed on each of the wafers in respective processing and treatment units in the processing block. Thereafter, each of the wafers is transferred via the interface block to the aligner and subjected to exposure processing. The wafer is then returned again into the processing block and subjected to predetermined processing and treatment such as the developing treatment and so on in the processing and treatment units. The wafers are then successively returned from the processing block to the transfer in/out block and housed into the cassette.
In the above-described coating and developing treatment system, processing adapted for a small lot is demanded because of diversification in device product in recent years. In this case, the number of wafers to be housed in one cassette is reduced, and therefore a larger number of cassettes need to wait in the system to transfer the wafers in the plurality of cassettes to the processing block so as not to make any time interval therebetween. Hence, it is proposed to provide a stocker for the cassettes, for example, in the processing system (Japanese Patent Application Laid-open No. 2000-124301).